The signal in the noise: stochastic models for Earth’s radiative imbalance, with implications for Earth’s climate sensitivity to greenhouse gases
Prof. Cristian Proistosescu
Department of Climate, Meteorology & Atmospheric Sciences
University of Illinois, Urbana-Champaign
Climate sensitivity quantifies the long-term warming the Earth will experience in response to the additional energy trapped by greenhouse gases. It is primarily determined by a parameter called the “net radiative feedback” or the “net radiative damping rate”: how much additional energy gets radiated to space by an additional degree of global warming. A strong damping rate means only a small amount of warming is necessary to balance the greenhouse gas induced energy surplus. Similarly, a weak damping rate implies a large amount of warming.
Unfortunately, the satellite record of Earth’s radiative budget is too short for direct estimates of the damping rate associated with greenhouse gas induced warming. However, the satellite record does contain significant stochastic variability in both temperature and radiation.
In this talk I will use a series of simple Langevin-type models to explain the observed stochastic variability and link it back to the net radiative feedback parameter that will ultimately determine the severity of global warming. This will be preceeded by a brief introduction to the basic physics of global warming.